Receiver devices or systems in a communication system may receive signals or waveforms which are distorted by interference or noise. Some wideband communication systems are supposed to work in the presence of strong narrowband interference.
Despite such narrowband interference, a receiving device must be able to detect a signal and determine its content. A receiving device must be able to align or synchronize the received signal in order to determine the start of a signal or message and/or to determine whether such signal contains a message.
However, many time domain and frequency domain synchronization algorithms fail in the presence of such interference. Some algorithms are more complex and some do not tolerate multiple interference. Some algorithms are very sensitive to the signal gain or require specific forms of symbols or patterns for synchronization.
Time domain correlation synchronizers may be used for synchronization but require many high-resolution multiplications for each received sample. For instance, 256×256 multiplications are required for a time domain correlation synchronizer for a synchronization symbol two hundred fifty-six (256) samples long.
Some time domain synchronizers use only the received signal sign to reduce the implementation complexity. However, such sign-based synchronizers often fail in the presence of strong narrowband interference.
Some frequency domain correlation synchronizers have to calculate the fast Fourier transform (FFT) coefficient of the signal on each coming time sample. This obviously is very complex to implement in real-time applications.
There is a frequency domain symbol synchronizer, which is based on only one time FFT calculation per symbol (each symbol comprising multiple time samples). However, this approach is based on calculation of FFT output phases and requires comparison with every possible phase settings to obtain the timing reference. Phase calculations and a large number of comparisons make this approach less attractive compared to the approach of the invention.